Intensification of Deep Hydrodesulfurization Through a Two-stage Combination of Monolith and Trickle Bed Reactors

Deep hydrodesulfurization （HDS） is an important process to produce high quality liquid fuels with ultra-low sul- fur. Process intensification for deep HDS could be implemented by developing new active catalysts and/or new types of reactors. In this work, the kinetics of dibenzothiophene （DBT） hydrodesulfurization over Ni-P/SBA-15/ cordierite catalyst was investigated at 340-380 ℃ and 3.0-5.0 MPa. The first-order reaction model with respect to both DBT and H2 was used to fit the kinetics data in a batch recycle operation system. It is found that both the activation energy and rate constant over the Ni-P monolithic catalyst under our operating conditions are close to those over conventionally used HDS catalysts. Comparative performance studies of two types of reactors, i.e., trickle bed reactor and monolithic reactor, were performed based on reactor modeling and simulation. The results indicate that the productivity of the monolithic reactor is 3 times higher than that of the trickle bed reactor on a catalyst weight basis since effective utilization of the catalyst is higher in the monolithic reactor, but the volumetric productivity of the monolithic reactor is lower for HDS of DBT. Based on simulation results, a two- reactor-in-series configuration for hydrodesulfurization is proposed, in which a monolithic reactor is followed by a tickled bed reactor so as to attain intensified performance of the system converting fuel oil of different sulfur-containing compounds. It is illustrated that the two reactor scheme outperforms the trickle bed reactor both on reactor volume and catalyst mass bases while the content of sulfur is reduced from 200 μg·g-1 to about 10 μ·g-1.

Process intensification in gas/liquid/solid reaction in trickle bed reactors: A review

As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.

Absorption Enhanced Methanol Synthesis in a Trickle Bed Reactor over Cu/Zn/Al₂O₃Catalyst

Methanol synthesis in a trickle bed reactor with tetraethylene glycol dimethyl ether (TEGDME) as the liquid phase over a Cu/Zn/Al2O3 catalyst was investigated. The pressure was kept constant at 5.0 MPa, while the temperature ranged from 230℃?to 260℃?and the mass space velocity varied between 294 L·Kg-1·h-1 and 1655 L·Kg-1·h-1. The effects of temperature and space velocity on CO conversion and methanol productivity were studied. Methanol synthesis processes in trickle bed with the TEGDME and paraffin oil as liquid phase were compared with the fixed bed process. The results indicated that the optimal temperature was approximately 240℃. When the space velocity was increased, the CO conversion decreased while the methanol productivity increased. The liquid introduced can help to keep the reactor nearly isothermal. For methanol synthesis in trickle-bed reactor, TEGDME was better than paraffin oil. Effect of TEGDME on the reaction was twofold. On one hand, it absorbs the methanol and speeds up the reaction. On the other hand, it also increases the mass transfer resistance and hinders the reaction.

HYSTERESIS OF GAS-LIQUID MASS TRANSFER IN A TRICKLE BED REACTOR

1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas and liquid flow cocurrently down through the packed bedand undergo chemical reactions.However,there exist multiple hydrodynamic stateswhich correspond to either uniform or,in most cases,nonuniform radial distributionof the gas and liquid flows in the packed section.Moreover,the hydrodynamic state

Application of Laplace Transform for a Gas-Liquid-Solid Trickle Bed Reactor by Using the Tracer Technique

Experimental evaluation and dynamic modelling were presented for a liquid flow (H2O + NaOH tracer) on solid particles in a trickle bed reactor. One-dimensional dynamic mathematical model has been described to study the gas-liquid-solid process in which the liquid phase with the NaOH tracer is treated as a continuum. The physical model has been analyzed, including the formulation of initial and boundary conditions and the description of the solution methodology. An experimental setup to measure the concentrations of the NaOH tracer has been performed. The concentration measurements of this NaOH tracer have been performed in a fixed be reactor on trickling flow of the liquid phase for a range of operating conditions. The axial dispersion (Dax) of the liquid phase, liquid-solid mass transfer (kLS) coefficient and partial wetting efficiency (fe) were chosen as the hydrodynamic parameters of the proposed mathematical model. Such parameters have been optimized with experimental measurents of the NaOH tracer at the exit of the trickle-bed reactor. The optimized parameters (Dax, kLS, and fe) were calculated simultaneously by using the theoretical model with minimization of the objective function. Results of the proposed mathematical model have been presented and compared as of the two experimental cases. These hydrodynamic parameters were fitted by means of the empirical correlations.

Liquid Phase Catalytic Oxidation of Aqueous Solutions That Contain Organic Matter in a Trickle-Bed Reactor

In this study, catalytic wet air oxidation of wastewater that contains organic matter (phenol) is investigated in a laboratory scale trickle-bed reactor. The aim of this project is to determine the optimum operating conditions for the reaction of phenol in the wastewater with oxygen using a catalyst. For this purpose, the effects of temperature, gas flow rate, liquid space velocity and initial concentration of phenol on the conversion of phenol at constant pressure and the effect of pressure on the conversion of phenol at constant temperature are investigated. An industrial copper chromite catalyst was used in the experimental studies. It is seen from the experimental results, conversion of phenol increases with increasing temperature, pressure, gas flow rate and liquid space velocity;and also, it is seen that conversion of phenol decreases with increasing initial concentration of phenol. The conversion of phenol reaches at 130?C and 4 bar to 40%. It was also found that, 3 ppm copper amount was determined from the exit stream of the reactor. This result shows that cupper placed in the structure of the catalyst, mixes with the liquid stream during the reaction.

Analysis of Operating Variables in the Catalytic Purification of Butene-1 in a Trickle Bed

A mathematical model for analyzing and simulating selective hydrogenation of butyne-1 and 1,3-bu-tadiene in industrial trickle bed reactors operated to obtain high purity butene-1 is presented in this work.Fromthe analysis of typical operating conditions,only the relevant phenomena are finally retained in the model formu-lation.The model is then employed to analyze the effect of operating variables and catalyst selectivity in processperformance.In particular,the search for the minimum hydrogen flow rate necessary to fulfil butene-1 purityspecifications is undertaken.

CORRELATION BETWEEN HYSTERESIS OF GAS-LIQUID MASS TRANSFER AND LIQUID DISTRIBUTION IN A TRICKLE BED

The hysteresis of gas-liquid mass transfer rate and the corresponding radial liquiddistribution in a trickle bed reactor are measured to provide evidence for the correlation between thesetwo behaviors.Experimental results indicate that the hysteresis of gas-liquid mass transfer originatesfrom the nonuniformity of the hydrodynamic state of gas-liquid flow and the radial maldistributionof local kgia corresponds very well to the radial maldistribution of liquid flow in the bed.The localliquid flow rate is also found to be nonuniform in the azimuthal direction.In view of maldistributedliquid flow even in the pulsing flow regime,the conventional plug flow model seems oversimplifiedfor describing the behavior of a trickle bed.

整体式催化剂性能及应用的研究进展

由整体式催化剂的结构特点出发,系统地阐述了整体式催化剂具有的一系列超越传统颗粒状催化剂的独特优越性,提出了其在三相反应中有待解决的几个关键性问题。同时概述了整体式催化剂在环保领域和化工产品合成领域的应用、研究现状和展望。

滴流床反应器中泡沫流床层压降的实验研究

选用过氧化氢生产用蒽醌工作液体系,完成了滴流床反应器中泡沫流床层压降的实验研究. 通过测定瞬时床层压降,建立了反应器内的流型识别方法,借以研究了在泡沫流和泡沫脉冲流区的床层压降梯度与气液相流速、填料尺寸的关系,并采用Specchia和Baldi提出的经验式对发泡体系泡沫流区床层压降进行了估算. 结果表明,通过实验数据回归,可采用Specchia和Baldi经验式预测泡沫流区的床层压降,最大偏差小于5%.

甘油三酯裂解制备可再生液体燃料油研究

以碳酸钠为碱性催化剂,采用TG、DTG、DSC分析确定大豆油为原料的裂解特性。通过对四种典型裂解产物的跟踪测定,确证碱性催化剂能够改变大豆油裂解时的反应历程。分析结果表明,裂解温度在400℃~500℃,热解方式为快速热解。采用自行研制的小型滴流床反应器催化裂解大豆油。比较了不同催化剂的催化裂解性能,发现碱性催化剂具有较高的脱羧能力。在较佳催化裂解工艺条件下,所得燃料油酸值较低（30 mg KOH/g）。通过FT-IR、GC-MS以及燃料性能的分析,其组分和成分与0号柴油相似,热值43 M J/kg,黏度2.6 mm2/s,密度0.84 g/cm3。

滴流床催化湿式氧化苯酚的动力学

通过自行设计制作的滴流床反应器 ,研究了苯酚在以CuO/γ Al2 O3 为催化剂的催化湿式氧化反应 .结果表明 ,在相对温和的操作条件 (温度 180℃ ,压力 3MPa,液相流量 1 6 6 8L·h-1,气相流量 16 0L·h-1)下 ,苯酚的去除率均达到 90 %以上 .苯酚的降解曲线与自催化反应的S型曲线类似 ,符合自由基链反应机理 .所建立的活塞流拟均相反应器模型能很好地拟合苯酚催化湿式氧化反应过程 .还研究了苯酚初始浓度、苯酚水溶液流量及反应温度对反应结果的影响 .

滴流床加氢裂化反应器内流体流动的数值模拟

采用计算流体力学(CFD)方法,利用Fluent软件中多孔介质模型对某实验室规模滴流床反应器进行数值模拟;对比考察3种多孔区域三相动量相互作用模型对计算结果的影响;通过模拟计算得到了反应器内速度场、压力场及持液量的详细信息,并对压降和持液量进行分析对比。结果表明,模拟计算结果与文献中实验报道结果相符,在3种动量相互作用模型中双流体界面力模型能描述床层的微观流动特征(壁流)。

喷射型分配器的性能研究

分配器是滴流床反应器的重要构件 ,分配器的性能与设计参数和操作条件有直接关系。通过对不同条件下喷射型分配器的性能试验发现 :操作负荷的增加 ,可以明显提高分配器的液体分配性能 ;粘度越低的液体 ,分配效果越好 ;提高喷淋点密度 ,有利于提高液体的分配效果 ;喷淋高度只在较低负荷时影响分配器的液体分配性能 ;喷射型分配器的压力降高于普通分配器。

滴流床反应器中丙烯水合醚化的研究

二异丙基醚是一种新的汽油含氧化合物抗爆添加剂。本文以滴流床反应器研究了丙烯直接水合醚化制取二异丙基醚。结果表明，有凝聚相存在的滴流床反应条件，使丙烯的转化率和二异丙基醚的选择性均优于气相反应；在１５０—１７４℃内，温度提高，丙烯转化率升高，二异丙基醚选择性下降，丙酮选择性升高；在６．０—８．０ＭＰａ内，压力提高，丙烯转化率和二异丙基醚选择性均升高；进料丙烯／水比降低，二异丙基醚选择性下降。产物异丙醇和二异丙基醚间存在平衡分布。催化剂活性在１００小时内较稳定，此后有所下降。

滴流床加氢法生产木糖醇的研究

本文对滴流床中压加氢生产木糖醇的工艺进行了研究。反应温度１２０℃，氢压４．０ＭＰａ，表观液速０．５ｍｍ／ｓ～２．０ｍｍ／ｓ。Ｒａｎｅｙ－Ｎｉ颗粒催化剂表层活化，床层内径１０ｍｍ。对平均粒径０．４７ｍｍ及０．６７ｍｍ的催化床层在低液速区反应特性进行了初步探讨。用简化模型计算的床层宏观效率因子比实际工业鼓泡床高８～９倍。其值随液速降低而上升，并存在多稳态的现象，与床层部分润湿现象一致。

催化湿式氧化法滴流床反应器处理污水的研究和应用

主要研究催化湿式氧化法滴流床反应器发展过程、研究进展和实际应用 ,论述了在湿式氧化法中滴流床反应器的特点和影响因素 ,并且对进一步的深入研究。

滴流床反应器内典型流型的特征与实验确定

分析了滴流床反应器内４ 种典型流动型式的特征。针对滴流床反应器内流体流动的情况，应用了一种新的实验方法检测４ 种典型的流型。从所测电导率的频谱特征上发现了各流型的特性区别：滴流、脉冲流和喷淋流流型电导率信号均有频率为３Ｈｚ 左右幅度较大的频率成分，各流型间频谱主要区别在０～３Ｈｚ频域内；鼓泡流流型电导信号频率主要分布在０～３Ｈｚ内。

滴流床反应器的非定态操作

采用蒽醌加氢反应为探针,研究了脉冲流操作、周期性填充和周期性操作3种非定态操作方式对TBR反应器性能的影响.结果表明,在脉冲流区操作TBR的催化剂质量空时收率比滴流区操作提高50%以上,表观动力学研究证实脉冲流区操作TBR蒽醌加氢反应的表观活化能比滴流区操作更接近本征活化能;催化剂与惰性颗粒的交替填充周期性地强化了气液相间传质速率,提高催化剂质量空时收率40%以上;反应器的周期性操作,同时强化气液和液固相间传质速率,改善反应器内的流体力学状况,从而提高反应的空时收率和选择性10%以上.